Fix trouble code P0400 – Ford Mercury Vehicles
A P0400 code indicates insufficient EGR flow. This could be caused by several things: restricted or carboned up passages, sticking pintle on EGR valve, or a problem with the vacuum supply to the EGR sensors.
The computer commands EGR operation and the Backpressure Transducer measures the pressure (or lack of it) to determine how well the EGR valve did in allowing EGR flow. The Transducer has several hoses going to it and this seems to be a common failure point in getting a P0400 code. So before you automatically assume that you have a bad EGR valve or carboned up passages, take a minute to closely examine the hoses going to the Exhaust Gas Backpressure Transducer. If you find on cracked or in bad shape, replace it. Also check to make sure all the hoses are attached to the proper port.
© 2012 Rick MuscoplatPosted on by Rick Muscoplat